1. Field of the Invention
The present invention relates to a printing apparatus, and more specifically to a control for determining the position of underscores placed below printed characters.
2. Discussion of the Prior Art
In a known printer, a recording paper is advanced by a suitable distance by feed rollers activated by a paper feeding device, before a desired portion of a printed line of characters is underscored by a print head. In this case, the underscore is located below the corresponding characters by the distance of feed of the paper in the direction perpendicular to the printing direction. In an alternative arrangement, underscores are printed simultaneously with the characters to be underscored, by a dot-matrix print head having a mutliplicity of printing elements which are arranged in a row in mutually spaced-apart relation in a direction perpendicular to the printing direction. In this case, a specific one of the printing elements is used for underscoring the characters.
In either of the above-indicated types of printer, a distance D1 between an underscore 2 and underscored characters 1 is constant, irrespective of an interline spacing D2 between the adjacent lines of characters, as illustrated in FIG. 4, that is, irrespective of a selected line spacing.
In the above underscoring arrangement, no problem arises where the interline spacing D2 is sufficiently large. However, in the case where the underscore 2 is printed in a printing operation with the line spacing D2 set at a relatively small value, the ratio of the character-to-underscore distance D1 to the interline spacing D2 may be excessively large, causing the underscore 2 to appear as a line separating the adjacent lines of characters, rather than an underline underlying the upper line of characters.